Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

Embodiments of the present invention include devices, systems and methods
for prevention of dropped calls. For example, a method for preventing
dropped voice calls can be performed by a base station. Multiple reports
are received from multiple wireless communication devices. A first
wireless communication device having a poor received signal is identified
using the reports. A sub-channel power imbalance ratio is adjusted so
that the base station gives favorable power imbalance to the first
wireless communication device over a second wireless communication
device. The second wireless communication device is paired with the first
wireless communication device. Adjusting the sub-channel power imbalance
ratio prevents a voice call by the first wireless communication device
from being dropped that would otherwise be dropped. Other aspects,
embodiments and features are also claimed and described.

Claims:

1. A method for preventing bad user experience and dropped voice calls,
wherein the method is performed by an access point, the method
comprising: identifying a first wireless communication device having a
poor received signal using multiple reports received from multiple
wireless communication devices; and adjusting a sub-channel power
imbalance ratio so that the access point gives a favorable power
imbalance to the first wireless communication device over a second
wireless communication device, wherein the second wireless communication
device is paired with the first wireless communication device, and
wherein adjusting the sub-channel power imbalance ratio prevents a voice
call by the first wireless communication device from being dropped that
would otherwise be dropped.

2. The method of claim 1, wherein the access point is configured to use
voice services over adaptive multi-user channels on one slot.

3. The method of claim 2, wherein the voice services over adaptive
multi-user channels on one slot enables the access point to support up to
four transmit channel/half rate channels along with their associated
control channels in one slot.

8. The method of claim 1, wherein the first wireless communication device
is allowed to operate in voice services over adaptive multi-user channels
on one slot mode.

9. The method of claim 1, wherein the second wireless communication
device misses one burst during the adjustment of the sub-channel power
imbalance ratio.

10. The method of claim 1, wherein the access point giving favorable
power imbalance to the first wireless communication device comprises
giving occasional and random favorable power imbalance to the first
wireless communication device.

13. An apparatus for preventing bad user experience and dropped voice
calls, comprising: a processor; memory in electronic communication with
the processor; and instructions stored in the memory, the instructions
being executable by the processor to: identify a first wireless
communication device having a poor received signal using multiple reports
received from multiple wireless communication devices; and adjust a
sub-channel power imbalance ratio so that the apparatus gives a favorable
power imbalance to the first wireless communication device over a second
wireless communication device, wherein the second wireless communication
device is paired with the first wireless communication device, and
wherein adjusting the sub-channel power imbalance ratio prevents a voice
call by the first wireless communication device from being dropped that
would otherwise be dropped.

14. The apparatus of claim 13, wherein the apparatus is a base station,
and wherein the apparatus is configured to use voice services over
adaptive multi-user channels on one slot.

15. The apparatus of claim 14, wherein the voice services over adaptive
multi-user channels on one slot enables the apparatus to support up to
four transmit channel/half rate channels along with their associated
control channels in one slot.

20. The apparatus of claim 13, wherein the first wireless communication
device operates in voice services over adaptive multi-user channels on
one slot mode.

21. The apparatus of claim 13, wherein the second wireless communication
device misses one burst during the adjustment of the sub-channel power
imbalance ratio.

22. The apparatus of claim 13, wherein the apparatus giving favorable
power imbalance to the first wireless communication device comprises
giving occasional and random favorable power imbalance to the first
wireless communication device.

25. A wireless device for preventing bad user experience dropped voice
calls, comprising: means for identifying a first wireless communication
device having a poor received signal using multiple reports received from
multiple wireless communication devices; and means for adjusting a
sub-channel power imbalance ratio so that the wireless device gives a
favorable power imbalance to the first wireless communication device over
a second wireless communication device, wherein the second wireless
communication device is paired with the first wireless communication
device, and wherein adjusting the sub-channel power imbalance ratio
prevents a voice call by the first wireless communication device from
being dropped that would otherwise be dropped.

26. The wireless device of claim 25, wherein the wireless device is a
base station, and wherein the wireless device is configured to use voice
services over adaptive multi-user channels on one slot.

27. The wireless device of claim 26, wherein the voice services over
adaptive multi-user channels on one slot enables the wireless device to
support up to four transmit channel/half rate channels along with their
associated control channels in one slot.

29. A computer-program product for preventing bad user experience and
dropped voice calls, the computer-program product comprising a
non-transitory computer-readable medium having instructions thereon, the
instructions comprising: code for causing an access point to identify a
first wireless communication device having a poor received signal using
multiple reports received from multiple wireless communication devices;
and code for causing the access point to adjust a sub-channel power
imbalance ratio so that the base station gives a favorable power
imbalance to the first wireless communication device over a second
wireless communication device, wherein the second wireless communication
device is paired with the first wireless communication device, and
wherein adjusting the sub-channel power imbalance ratio prevents a voice
call by the first wireless communication device from being dropped that
would otherwise be dropped.

30. The computer-program product of claim 29, wherein the access point is
a base station, and wherein the base station is using voice services over
adaptive multi-user channels on one slot.

31. The computer-program product of claim 30, wherein the voice services
over adaptive multi-user channels on one slot allows the base station to
support up to four transmit channel/half rate channels along with their
associated control channels in one slot.

33. An apparatus configured for preventing bad user experience and
dropped voice calls, the apparatus comprising: a processor; memory in
electronic communication with the processor; and instructions stored in
the memory, the instructions being executable by the processor to:
discern changes in adaptive quadrature phase shift keying/sub-channel
power imbalance ratio implemented by a base station; and perform adaptive
burst processing according to the changes.

34. The apparatus of claim 33, wherein the apparatus is a wireless
communication device.

35. The apparatus of claim 33, wherein the adaptive burst processing
provides a bit error rate that prevents a voice call by from being
dropped.

36. The apparatus of claim 33, wherein the adaptive burst processing
provides a frame error rate that prevents a voice call by from being
dropped.

37. A wireless device for preventing bad user experience and dropped
voice calls, comprising: means for discerning changes in adaptive
quadrature phase shift keying/sub-channel power imbalance ratio
implemented by a base station; and means for performing adaptive burst
processing according to the changes.

38. The wireless device of claim 37, wherein the wireless device is a
wireless communication device.

39. The wireless device of claim 38, wherein the adaptive burst
processing provides a bit error rate that prevents a voice call by from
being dropped.

40. The wireless device of claim 39, wherein the adaptive burst
processing provides a frame error rate that prevents a voice call by from
being dropped.

Description:

RELATED APPLICATIONS AND PRIORITY CLAIM

[0001] This application is related to and claims priority from U.S.
Provisional Patent Application Ser. No. 61/446,401, filed Feb. 24, 2011,
for "PREVENTING DROPPED CALLS USING VOICE SERVICES OVER ADAPTIVE
MULTI-USER CHANNELS ON ONE SLOT (VAMOS) MODE," which is incorporated
herein by reference.

TECHNICAL FIELD

[0002] Embodiments of the present invention relate generally to
communication systems. More specifically, embodiments of the present
invention relate to systems and methods for preventing dropped calls
using voice services over adaptive multi-user channels on one slot
(VAMOS) mode. Embodiments of the present invention may be utilized within
wireless communication systems, devices, methods, and articles of
manufacture for communication components.

BACKGROUND

[0003] Wireless communication systems have become an important means by
which many people worldwide have come to communicate. A wireless
communication system may provide communication for a number of subscriber
stations, each of which may be serviced by a base station.

[0004] New subscriber stations are continuously being released to the
public. These new subscriber stations boast more features and increased
reliability. However, older subscriber stations continue to be used by
consumers. These older subscriber stations may be collectively referred
to as legacy devices. As updates are made to the base stations, the
operation of these legacy devices may be considered, as the legacy
devices are still being actively used by paying consumers of the wireless
communication systems.

[0005] One major concern for users of subscriber stations is the frequency
of dropped calls. Dropped calls reduce the satisfaction rate of wireless
communication providers. Benefits may be realized by reducing the
frequency of dropped calls for subscriber stations, including legacy
devices.

SUMMARY OF SOME EXAMPLE EMBODIMENTS

[0006] A method for preventing bad user experience and dropped voice calls
is described. The method is performed by an access point. A first
wireless communication device having a poor received signal is identified
using multiple reports received from multiple wireless communication
devices. A sub-channel power imbalance ratio is adjusted so that the
access point gives a favorable power imbalance to the first wireless
communication device over a second wireless communication device. The
second wireless communication device is paired with the first wireless
communication device. Adjusting the sub-channel power imbalance ratio
prevents a voice call by the first wireless communication device from
being dropped that would otherwise be dropped.

[0007] The access point may be configured to use voice services over
adaptive multi-user channels on one slot. The voice services over
adaptive multi-user channels on one slot may enable the access point to
support up to four transmit channel/half rate channels along with their
associated control channels in one slot. The voice services over adaptive
multi-user channels on one slot may use adaptive quadrature phase shift
keying. The reports may be slow associated control channel reports.

[0008] The first wireless communication device may be a legacy wireless
communication device or a downlink advanced receiver performance wireless
communication device. The first wireless communication device may be
allowed to operate in voice services over adaptive multi-user channels on
one slot mode. The second wireless communication device may miss one
burst during the adjustment of the sub-channel power imbalance ratio.

[0009] The access point giving favorable power imbalance to the first
wireless communication device may include giving occasional and random
favorable power imbalance to the first wireless communication device.
Adjusting a sub-channel power imbalance ratio may give Gaussian minimum
shift keying to the first wireless communication device. Adjusting a
sub-channel power imbalance ratio may instead give favorable adaptive
quadrature shift keying to the first wireless communication device.

[0010] An apparatus for preventing bad user experience and dropped voice
calls is also described. The apparatus includes a processor, memory in
electronic communication with the processor and instructions stored in
the memory. The instructions are executable by the processor to identify
a first wireless communication device having a poor received signal using
multiple reports received from multiple wireless communication devices.
The instructions are also executable by the processor to adjust a
sub-channel power imbalance ratio so that the apparatus gives a favorable
power imbalance to the first wireless communication device over a second
wireless communication device. The second wireless communication device
is paired with the first wireless communication device. Adjusting the
sub-channel power imbalance ratio prevents a voice call by the first
wireless communication device from being dropped that would otherwise be
dropped.

[0011] The apparatus may be a base station configured to use voice
services over adaptive multi-user channels on one slot.

[0012] A wireless device for preventing bad user experience dropped voice
calls is described. The wireless device includes means for identifying a
first wireless communication device having a poor received signal using
multiple reports received from multiple wireless communication devices.
The wireless device also includes means for adjusting a sub-channel power
imbalance ratio so that the wireless device gives a favorable power
imbalance to the first wireless communication device over a second
wireless communication device. The second wireless communication device
is paired with the first wireless communication device. Adjusting the
sub-channel power imbalance ratio prevents a voice call by the first
wireless communication device from being dropped that would otherwise be
dropped.

[0013] A computer-program product for preventing bad user experience and
dropped voice calls is also described. The computer-program product
includes a non-transitory computer-readable medium having instructions
thereon. The instructions include code for causing an access point to
identify a first wireless communication device having a poor received
signal using multiple reports received from multiple wireless
communication devices. The instructions also include code for causing the
access point to adjust a sub-channel power imbalance ratio so that the
base station gives a favorable power imbalance to the first wireless
communication device over a second wireless communication device. The
second wireless communication device is paired with the first wireless
communication device. Adjusting the sub-channel power imbalance ratio
prevents a voice call by the first wireless communication device from
being dropped that would otherwise be dropped.

[0014] An apparatus configured for preventing bad user experience and
dropped voice calls is described. The apparatus includes a processor,
memory in electronic communication with the processor and instructions
stored in the memory. The instructions are executable by the processor to
discern changes in adaptive quadrature phase shift keying/sub-channel
power imbalance ratio implemented by a base station. The instructions are
also executable by the processor to perform adaptive burst processing
according to the changes.

[0015] The apparatus may be a wireless communication device. The adaptive
burst processing can result in a bit error rate and/or frame error rate
that prevents a phone call from being dropped or from providing
unintelligible voice call quality for end users.

[0016] A wireless device for preventing bad user experience and dropped
voice calls is also described. The wireless device includes means for
discerning changes in adaptive quadrature phase shift keying/sub-channel
power imbalance ratio implemented by a base station. The wireless device
also includes means for performing adaptive burst processing according to
the changes. The adaptive burst processing can result in a bit error rate
and/or frame error rate that prevents a phone call from being dropped or
from providing unintelligible voice call quality for end users.

[0017] Other aspects, features, and embodiments of the present invention
will become apparent to those of ordinary skill in the art, upon
reviewing the following description of specific, exemplary embodiments of
the present invention in conjunction with the accompanying figures. While
features of the present invention may be discussed relative to certain
embodiments and figures below, all embodiments of the present invention
can include one or more of the advantageous features discussed herein. In
other words, while one or more embodiments may be discussed as having
certain advantageous features, one or more of such features may also be
used in accordance with the various embodiments of the invention
discussed herein. In similar fashion, while exemplary embodiments may be
discussed below as device, system, or method embodiments it should be
understood that such exemplary embodiments can be implemented in various
devices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 shows an example of a wireless communication system in which
embodiments of the present invention disclosed herein may be utilized
according to some embodiments of the present invention;

[0019]FIG. 2 shows a block diagram of a transmitter and a receiver in a
wireless communication system according to some embodiments of the
present invention;

[0020]FIG. 3 shows a block diagram of a design of a receiver unit and
demodulator at a receiver according to some embodiments of the present
invention;

[0021]FIG. 4 shows example frame and burst formats in GSM according to
some embodiments of the present invention;

[0022]FIG. 5 shows an example spectrum in a GSM system according to some
embodiments of the present invention;

[0023]FIG. 6 illustrates an example of a wireless device that includes
transmit circuitry (including a power amplifier), receive circuitry, a
power controller, a decode processor, a processing unit for use in
processing signals and memory according to some embodiments of the
present invention;

[0024]FIG. 7 illustrates an example of a transmitter structure and/or
process according to some embodiments of the present invention;

[0025]FIG. 8 is a block diagram illustrating some of the elements of the
GERAN stack that are used to support voice services over adaptive
multi-user channels on one slot (VAMOS) according to some embodiments of
the present invention;

[0026]FIG. 9 is a block diagram illustrating how, in some embodiments,
different numbers of users may be served in a timeslot using voice
services over adaptive multi-user channels on one slot (VAMOS) according
to some embodiments of the present invention;

[0027]FIG. 10 is a block diagram illustrating one embodiment of the voice
services over adaptive multi-user channels on one slot (VAMOS) downlink
physical layer functionality of a base station according to some
embodiments of the present invention;

[0028]FIG. 11 is a flow diagram of a method for preventing dropped voice
calls according to some embodiments of the present invention;

[0029]FIG. 12 illustrates two adaptive quadrature phase shift keying
(AQPSK) constellations according to some embodiments of the present
invention;

[0030]FIG. 13 illustrates certain components that may be included within
a base station according to some embodiments of the present invention;
and

[0031]FIG. 14 illustrates certain components that may be included within
a wireless communication device according to some embodiments of the
present invention.

DETAILED DESCRIPTION OF EXEMPLARY & ALTERNATIVE EMBODIMENTS

[0032] More and more people are using wireless communication devices, such
as, mobile phones, not only for voice but also for data communications.
Telecommunications networks are being placed under increasing strain,
both due to increasing bandwidth requirements of smartphones and mobile
computers, and the increasing numbers devices and programs that seek
access to the networks. For example, many applications running on
smartphones periodically access the network to check for updates. While
each access itself only consumes a relatively small amount of bandwidth,
large numbers of devices running lots of applications can place a
significant load on networks, and signaling and control channels in
particular. The increasing prevalence of machine type communication (MTC)
devices (e.g., machine-to-machine (M2M)) can similarly increase the
demands placed upon network resources.

[0033]FIG. 1 shows an example of a wireless communication system 100 in
which embodiments of the present invention disclosed herein may be
utilized. The wireless communication system 100 includes multiple base
stations 102 and multiple wireless communication devices 104. Each base
station 102 provides communication coverage for a particular geographic
area 106. The term "cell" can refer to a base station 102 and/or its
coverage area 106 depending on the context in which the term is used.

[0034] The terms "wireless communication device" and "base station"
utilized in this application can generally refer to an array of
components. For example, as used herein, the term "wireless communication
device" refers to an electronic device that may be used for voice and/or
data communication over a wireless communication system. Examples of
wireless communication devices 104 include cellular phones, personal
digital assistants (PDAs), handheld devices, wireless modems, laptop
computers and personal computers. A wireless communication device 104 may
alternatively be referred to as an access terminal, a mobile terminal, a
mobile station, a remote station, a user terminal, a terminal, a
subscriber unit, a subscriber station, a mobile device, a wireless
device, user equipment (UE), or some other similar terminology. Also, the
term "base station" can refer to a wireless communication station that is
installed at a fixed location and used to communicate with wireless
communication devices 104. A base station 102 may alternatively be
referred to as an access point (including nano-, pico- and femto-cells),
a Node B, an evolved Node B, a Home Node B or some other similar
terminology.

[0035] To improve system capacity, a base station coverage area 106 may be
partitioned into plural smaller areas, e.g., three smaller areas 108a,
108b, and 108c. Each smaller area 108a, 108b, 108c may be served by a
respective base transceiver station (BTS). The term "sector" can refer to
a BTS and/or its coverage area 108 depending on the context in which the
term is used. For a sectorized cell, the BTSs for all sectors of that
cell are typically co-located within the base station 102 for the cell.

[0036] Wireless communication devices 104 are typically dispersed
throughout the wireless communication system 100. A wireless
communication device 104 may communicate with one or more base stations
102 on the downlink and/or uplink at any given moment. The downlink (or
forward link) refers to the communication link from a base station 102 to
a wireless communication device 104, and the uplink (or reverse link)
refers to the communication link from a wireless communication device 104
to a base station 102. Uplink and downlink may refer to the communication
link or to the carriers used for the communication link.

[0037] For a centralized architecture, a system controller 110 may couple
to the base stations 102 and provide coordination and control for the
base stations 102. The system controller 110 may be a single network
entity or a collection of network entities. As another example, for a
distributed architecture, base stations 102 may communicate with one
another as needed.

[0038]FIG. 2 shows a block diagram of a transmitter 271 and a receiver
273 in a wireless communication system 100 according to some embodiments
of the present invention. For the downlink, the transmitter 271 may be
part of a base station 102 and the receiver 273 may be part of a wireless
communication device 104. For the uplink, the transmitter 271 may be part
of a wireless communication device 104 and the receiver 273 may be part
of a base station 102.

[0040] At the receiver 273, an antenna 222 receives RF modulated signals
from the transmitter 271 and other transmitters. The antenna 222 provides
a received RF signal to a receiver unit (RCVR) 224. The receiver unit 224
conditions (e.g., filters, amplifies, and downconverts) the received RF
signal, digitizes the conditioned signal, and provides samples. A
demodulator 226 processes the samples as described below and provides
demodulated data 232. A receive (RX) data processor 228 processes (e.g.,
deinterleaves and decodes) the demodulated data and provides decoded
data. In general, the processing by demodulator 226 and RX data processor
228 is complementary to the processing by the modulator 212 and the TX
data processor 275, respectively, at the transmitter 271.

[0041] Controllers/processors 214 and 234 direct operation at the
transmitter 271 and receiver 273, respectively. Memories 216 and 236
store program codes in the form of computer software and data used by the
transmitter 271 and receiver 273, respectively.

[0042]FIG. 3 shows a block diagram of a design of a receiver unit 324 and
a demodulator 326 at a receiver 273. Within the receiver unit 324, a
receive chain 327 processes the received RF signal and provides I
(inphase) and Q (quadrature) baseband signals, which are denoted as
Ibb and Qbb. The receive chain 327 may perform low noise
amplification, analog filtering, quadrature downconversion, etc. as
desired or needed. An analog-to-digital converter (ADC) 328 digitalizes
the I and Q baseband signals at a sampling rate of fadc from a
sampling clock 329 and provides I and Q samples, which are denoted as
Iadc and Qadc. In general, the ADC sampling rate fadc may
be related to the symbol rate fsym by any integer or non-integer
factor.

[0043] Within the demodulator 326, a pre-processor 330 performs
pre-processing on the I and Q samples from the analog-to-digital
converter (ADC) 328. For example, the pre-processor 330 may remove direct
current (DC) offset, remove frequency offset, etc. An input filter 332
filters the samples from the pre-processor 330 based on a particular
frequency response and provides input I and Q samples, which are denoted
as Iin and Qin. The input filter 332 may filter the I and Q
samples to suppress images resulting from the sampling by the
analog-to-digital converter (ADC) 328 as well as jammers. The input
filter 332 may also perform sample rate conversion, e.g., from 24×
oversampling down to 2× oversampling. A data filter 333 filters the
input I and Q samples from the input filter 332 based on another
frequency response and provides output I and Q samples, which are denoted
as Iout and Qout. The input filter 332 and the data filter 333
may be implemented with finite impulse response (FIR) filters, infinite
impulse response (IIR) filters, or filters of other types. The frequency
responses of the input filter 332 and the data filter 333 may be selected
to achieve good performance. In one design, the frequency response of the
input filter 332 is fixed and the frequency response of the data filter
333 is configurable.

[0044] An adjacent-channel-interference (ACI) detector 334 receives the
input I and Q samples from the input filter 332, detects for
adjacent-channel-interference (ACI) in the received RF signal, and
provides an adjacent-channel-interference (ACI) indicator 336 to the data
filter 333. The adjacent-channel-interference (ACI) indicator 336 may
indicate whether or not adjacent-channel-interference (ACI) is present
and, if present, whether the adjacent-channel-interference (ACI) is due
to the higher RF channel centered at +200 kilohertz (kHz) and/or the
lower RF channel centered at -200 kHz. The frequency response of the data
filter 333 may be adjusted based on the adjacent-channel-interference
(ACI) indicator 336, to achieve desirable performance.

[0045] An equalizer/detector 335 receives the output I and Q samples from
the data filter 333 and performs equalization, matched filtering,
detection and/or other processing on these samples. For example, the
equalizer/detector 335 may implement a maximum likelihood sequence
estimator (MLSE) that determines a sequence of symbols that is most
likely to have been transmitted given a sequence of I and Q samples and a
channel estimate.

[0046] The Global System for Mobile Communications (GSM) is a widespread
standard in cellular, wireless communication. GSM is relatively efficient
for standard voice services. However, high-fidelity audio and data
services require higher data throughput rates than that for which GSM is
optimized. To increase capacity, the General Packet Radio Service (GPRS),
EDGE (Enhanced Data rates for GSM Evolution) and UMTS (Universal Mobile
Telecommunications System) standards have been adopted in GSM systems. In
the GSM/EDGE Radio Access Network (GERAN) specification, GPRS and EGPRS
provide data services. The standards for GERAN are maintained by the 3GPP
(Third Generation Partnership Project). GERAN is a part of GSM. More
specifically, GERAN is the radio part of GSM/EDGE together with the
network that joins the base stations 102 (the Ater and Abis interfaces)
and the base station controllers (A interfaces, etc.). GERAN represents
the core of a GSM network. It routes phone calls and packet data from and
to the PSTN (Public Switched Telephone Network) and Internet to and from
remote terminals. GERAN is also a part of combined UMTS/GSM networks.

[0047] GSM employs a combination of Time Division Multiple Access (TDMA)
and Frequency Division Multiple Access (FDMA) for the purpose of sharing
the spectrum resource. GSM networks typically operate in a number of
frequency bands. For example, for uplink communication, GSM-900 commonly
uses a radio spectrum in the 890-915 megahertz (MHz) bands (Mobile
Station to Base Transceiver Station). For downlink communication, GSM 900
uses 935-960 MHz bands (base station 102 to wireless communication device
104). Furthermore, each frequency band is divided into 200 kHz carrier
frequencies providing 124 RF channels spaced at 200 kHz. GSM-1900 uses
the 1850-1910 MHz bands for the uplink and 1930-1990 MHz bands for the
downlink. Like GSM 900, FDMA divides the spectrum for both uplink and
downlink into 200 kHz-wide carrier frequencies. Similarly, GSM-850 uses
the 824-849 MHz bands for the uplink and 869-894 MHz bands for the
downlink, while GSM-1800 uses the 1710-1785 MHz bands for the uplink and
1805-1880 MHz bands for the downlink.

[0049] Each channel in GSM is identified by a specific absolute radio
frequency channel (ARFCN). For example, ARFCN 1-124 are assigned to the
channels of GSM 900, while ARFCN 512-810 are assigned to the channels of
GSM 1900. Similarly, ARFCN 128-251 are assigned to the channels of GSM
850, while ARFCN 512-885 are assigned to the channels of GSM 1800. Also,
each base station 102 is assigned one or more carrier frequencies. Each
carrier frequency is divided into eight time slots (which are labeled as
time slots 0 through 7) using TDMA such that eight consecutive time slots
form one TDMA frame with a duration of 4.615 milliseconds (ms). A
physical channel occupies one time slot within a TDMA frame. Each active
wireless communication device 104 or user is assigned one or more time
slot indices for the duration of a call. User-specific data for each
wireless communication device 104 is sent in the time slot(s) assigned to
that wireless communication device 104 and in TDMA frames used for the
traffic channels.

[0050]FIG. 4 shows example frame and burst formats in GSM. The timeline
for transmission is divided into multiframes 437. For traffic channels
used to transmit user-specific data, each multiframe 437 in this example
includes 26 TDMA frames 438, which are labeled as TDMA frames 0 through
25. The traffic channels are sent in TDMA frames 0 through 11 and TDMA
frames 13 through 24 of each multiframe 437. A control channel is sent in
TDMA frame 12. No data is sent in idle TDMA frame 25, which is used by
the wireless communication devices 104 to make measurements of signals
transmitted by neighbor base stations 102.

[0051] Each time slot within a frame is also referred to as a "burst" 439
in GSM. Each burst 439 includes two tail fields, two data fields, a
training sequence (or midamble) field and a guard period (GP). The number
of symbols in each field is shown inside the parentheses. A burst 439
includes symbols for the tail, data, and midamble fields. No symbols are
sent in the guard period. TDMA frames of a particular carrier frequency
are numbered and formed in groups of 26 or 51 TDMA frames 438 called
multiframes 437.

[0052]FIG. 5 shows an example spectrum 500 in a GSM system. In this
example, five RF modulated signals are transmitted on five RF channels
that are spaced apart by 200 kHz. The RF channel of interest is shown
with a center frequency of 0 Hz. The two adjacent RF channels have center
frequencies that are +200 kHz and -200 kHz from the center frequency of
the desired RF channel. The next two nearest RF channels (which are
referred to as blockers or non-adjacent RF channels) have center
frequencies that are +400 kHz and -400 kHz from the center frequency of
the desired RF channel. There may be other RF channels in the spectrum
500, which are not shown in FIG. 5 for simplicity. In GSM, an RF
modulated signal is generated with a symbol rate of
fsym=13000/40=270.8 kilo symbols/second (ksps) and has a -3 decibel
(dB) bandwidth of up to 135 kHz. The RF modulated signals on adjacent RF
channels may thus overlap one another at the edges, as shown in FIG. 5.

[0053] In GSM/EDGE, frequency bursts (FB) are sent regularly by the base
station 102 to allow wireless communication devices 104 to synchronize
their local oscillator (LO) to the base Station 102 local oscillator
(LO), using frequency offset estimation and correction. These bursts
comprise a single tone, which corresponds to all "0" payload and training
sequence. The all zero payload of the frequency burst is a constant
frequency signal, or a single tone burst. When in power mode, the
wireless communication device 104 hunts continuously for a frequency
burst from a list of carriers. Upon detecting a frequency burst, the
wireless communication device 104 will estimate the frequency offset
relative to its nominal frequency, which is 67.7 kHz from the carrier.
The wireless communication device 104 local oscillator (LO) will be
corrected using this estimated frequency offset. In power up mode, the
frequency offset can be as much as 19/kHz. The wireless communication
device 104 will periodically wakeup to monitor the frequency burst to
maintain its synchronization in standby mode. In the standby mode, the
frequency offset is within ±2 kHz.

[0054] One or more modulation schemes are used in GERAN systems to
communicate information such as voice, data, and/or control information.
Examples of the modulation schemes may include GMSK (Gaussian Minimum
Shift Keying), M-ary QAM (Quadrature Amplitude Modulation) or M-ary PSK
(Phase Shift Keying), where M=2n, with n being the number of bits
encoded within a symbol period for a specified modulation scheme. GMSK is
a constant envelope binary modulation scheme allowing raw transmission at
a maximum rate of 270.83 kilobits per second (Kbps).

[0055] General Packet Radio Service (GPRS) is a non-voice service. It
allows information to be sent and received across a mobile telephone
network. It supplements Circuit Switched Data (CSD) and Short Message
Service (SMS). GPRS employs the same modulation schemes as GSM. GPRS
allows for an entire frame (all eight time slots) to be used by a single
mobile station at the same time. Thus, higher data throughput rates are
achievable.

[0056] The EDGE standard uses both the GMSK modulation and 8-PSK
modulation. Also, the modulation type can be changed from burst to burst.
8-PSK modulation in EDGE is a linear, 8-level phase modulation with
3π/8 rotation, while GMSK is a non-linear, Gaussian-pulse-shaped
frequency modulation. However, the specific GMSK modulation used in GSM
can be approximated with a linear modulation (i.e., 2-level phase
modulation with a π/2 rotation). The symbol pulse of the approximated
GSMK and the symbol pulse of 8-PSK are identical. The EGPRS2 standard
uses GMSK, QPSK, 8-PSK, 16-QAM and 32-QAM modulations. The modulation
type can be changed from burst to burst. Q-PSK, 8-PSK, 16-QAM and 32-QAM
modulations in EGPRS2 are linear, 4-level, 8-level, 16-level and 32-level
phase modulations with 3π/4, 3π/8, π/4, -π/4 rotation, while
GMSK is a non-linear, Gaussian-pulse-shaped frequency modulation.
However, the specific GMSK modulation used in GSM can be approximated
with a linear modulation (i.e., 2-level phase modulation with a π/2
rotation). The symbol pulse of the approximated GSMK and the symbol pulse
of 8-PSK are identical. The symbol pulse of Q-PSK, 16-QAM and 32-QAM can
use spectrally narrow or wide pulse shapes.

[0057]FIG. 6 illustrates an example of a wireless device 600 that
includes transmit circuitry 641 (including a power amplifier 642),
receive circuitry 643, a power controller 644, a decode processor 645, a
processing unit 646 for use in processing signals and memory 647. The
wireless device 600 may be a base station 102 or a wireless communication
device 104. The transmit circuitry 641 and the receive circuitry 643 may
allow transmission and reception of data, such as audio communications,
between the wireless device 600 and a remote location. The transmit
circuitry 641 and receive circuitry 643 may be coupled to an antenna 640.

[0058] The processing unit 646 controls operation of the wireless device
600. The processing unit 646 may also be referred to as a central
processing unit (CPU). Memory 647, which may include both read-only
memory (ROM) and random access memory (RAM), provides instructions and
data to the processing unit 646. A portion of the memory 647 may also
include non-volatile random access memory (NVRAM).

[0059] The various components of the wireless device 600 are coupled
together by a bus system 649 which may include a power bus, a control
signal bus, and a status signal bus in addition to a data bus. For the
sake of clarity, the various busses are illustrated in FIG. 6 as the bus
system 649.

[0060] The steps of the methods discussed may also be stored as
instructions in the form of software or firmware located in memory 647 in
a wireless device 600. These instructions may be executed by the
controller/processor(s) 110 of the wireless device 600. Alternatively, or
in conjunction, the steps of the methods discussed may be stored as
instructions in the form of software or firmware 648 located in memory
647 in the wireless device 600. These instructions may be executed by the
processing unit 646 of the wireless device 600 in FIG. 6.

[0061]FIG. 7 illustrates an example of a transmitter structure and/or
process. The transmitter structure and/or process of FIG. 7 may be
implemented in a wireless device such as a wireless communication device
104 or a base station 102. The functions and components shown in FIG. 7
may be implemented by software, hardware or a combination of software and
hardware. Other functions may be added to FIG. 7 in addition to or
instead of the functions shown.

[0062] In FIG. 7, a data source 750 provides data d(t) 751 to a frame
quality indicator (FQI)/encoder 752. The frame quality indicator
(FQI)/encoder 752 may append a frame quality indicator (FQI) such as a
cyclic redundancy check (CRC) to the data d(t). The frame quality
indicator (FQI)/encoder 752 may further encode the data and frame quality
indicator (FQI) using one or more coding schemes to provide encoded
symbols 753. Each coding scheme may include one or more types of coding,
e.g., convolutional coding, Turbo coding, block coding, repetition
coding, other types of coding or no coding at all. Other coding schemes
may include automatic repeat request (ARQ), hybrid ARQ (H-ARQ) and
incremental redundancy repeat techniques. Different types of data may be
encoded with different coding schemes.

[0063] An interleaver 754 interleaves the encoded data symbols 753 in time
to combat fading and generates symbols 755. The interleaved symbols 755
may be mapped by a frame format block 756 to a pre-defined frame format
to produce a frame 757. In an example, a frame format block 756 may
specify the frame 757 as being composed of a plurality of sub-segments.
Sub-segments may be any successive portions of a frame 757 along a given
dimension, e.g., time, frequency, code or any other dimension. A frame
757 may be composed of a fixed plurality of such sub-segments, each
sub-segment containing a portion of the total number of symbols allocated
to the frame. In one example, the interleaved symbols 755 are segmented
into a plurality S of sub-segments making up a frame 757.

[0064] A frame format block 756 may further specify the inclusion of,
e.g., control symbols (not shown) along with the interleaved symbols 755.
Such control symbols may include, e.g., power control symbols, frame
format information symbols, etc.

[0066] A baseband-to-radio-frequency (RF) conversion block 760 may convert
the modulated data 759 to RF signals for transmission via an antenna 761
as signal 762 over a wireless communication link to one or more wireless
device receivers.

[0067]FIG. 8 is a block diagram illustrating some of the elements of the
GERAN stack that are used to support voice services over adaptive
multi-user channels on one slot (VAMOS) in some embodiments of the
present invention. The non-access stratum (NAS) layer 863 may include the
voice services over adaptive multi-user channels on one slot (VAMOS)
radio capability classmark. The non-access stratum (NAS) layer 863 may
send information to the mobility management (MM)/GPRS mobility management
(GMM) layer 864. The mobility management (MM)/GPRS mobility management
(GMM) layer 864 may communicate with a logical link control (LLC) layer
866 in data services 865. The mobility management (MM)/GPRS mobility
management (GMM) layer 864 may also communicate with a radio resources
(RR)/GPRS radio resources (GRR) layer 870.

[0068] The data services 865 may also include a radio link control (RLC)
layer 867 for uplink 868 and downlink 869 communications. The radio link
control (RLC) layer 867 may communicate with the logical link control
(LLC) layer 866 and the radio resources (RR)/GPRS radio resources (GRR)
layer 870. The logical link control (LLC) layer 866 may also communicate
with the radio resources (RR)/GPRS radio resources (GRR) layer 870. The
radio link control (RLC) layer 867 may also communicate with a General
Packet Radio Service (GPRS) Portable Layer 1 (PL1) 875 of the portable
layer 1 873. The portable layer 1 873 may include the General Packet
Radio Service (GPRS) Portable Layer 1 (PL1) 875 and the Global Systems
for Mobile Communication (GSM) Portable Layer 1 (PL1) 874. The radio
resources (RR)/GPRS radio resources (GRR) layer 870 may communicate
directly with the portable layer 1 873.

[0069] The radio resources (RR)/GPRS radio resources (GRR) layer 870 may
also communicate with the Global Systems for Mobile Communication (GSM)
Portable Layer 1 (PL1) 874 via an L2 layer 872. The radio resources
(RR)/GPRS radio resources (GRR) layer 870 may communicate with a media
access control (MAC) layer 878 via a Circuit Switched Network (CSN)
Utility 871. The radio resources (RR)/GPRS radio resources (GRR) layer
870 may also communicate directly with the media access control (MAC)
layer 878. The media access control (MAC) layer 878 may communicate with
both the radio link control (RLC) layer 867 and the General Packet Radio
Service (GPRS) Portable Layer 1 (PL1) 875. The portable layer 1 873 may
communicate with a non-portable layer 1 876. The non-portable layer 1 876
may then communicate with a modem digital signal processor (mDSP) 877.

[0070]FIG. 9 is a block diagram illustrating how, in some embodiments,
different numbers of users may be served in timeslots 979 using voice
services over adaptive multi-user channels on one slot (VAMOS). In a
non-VAMOS slot 978a, one full rate speech (FR) wireless communication
device 104 may be served using Gaussian minimum shift keying (GMSK). Or,
in a non-VAMOS slot 978b, two half rate speech (HR) wireless
communication devices 104 may be served using Gaussian minimum shift
keying (GMSK). In voice services over adaptive multi-user channels on one
slot (VAMOS), two wireless communication devices 104 may be paired using
adaptive quadrature phase shift keying (AQPSK) on the downlink 869 while
using Gaussian minimum shift keying (GMSK) unchanged on the uplink 868.
Thus, two full rate speech (FR) and four half rate speech (HR) wireless
communication devices 104 can be served on one timeslot 979. Voice
services over adaptive multi-user channels on one slot (VAMOS) are
compatible with legacy wireless communication devices 104 and can make
use of well the established downlink advanced receiver performance (DARP)
feature. As used herein, legacy wireless communication devices 104 refers
to downlink advanced receiver performance (DARP) phones and pre-DARP
phones. In some cases, using voice services over adaptive multi-user
channels on one slot (VAMOS) may double the capacity or achieve the same
capacity using half the spectrum when compared to the standard Global
Systems for Mobile Communication (GSM) framework.

[0071] The voice services over adaptive multi-user channels on one slot
(VAMOS) feature was introduced in 3GPP GERAN Release 9 standards in order
to improve the spectrum efficiency for Circuit Switched (CS) connections.
Voice services over adaptive multi-user channels on one slot (VAMOS) may
only be applicable to the Circuit Switched (CS) voice service and not the
Packet Switched (PS) data service.

[0072] Voice services over adaptive multi-user channels on one slot
(VAMOS) may serve two wireless communication devices 104 simultaneously
on the same physical resources (i.e., on the same timeslot and the same
absolute radio-frequency channel number (ARFCN)) in the circuit switched
mode both in the downlink 869 and in the uplink 868 in one embodiment.
Hence, a basic physical channel capable of voice services over adaptive
multi-user channels on one slot (VAMOS) may support up to four transmit
channel (TCH)/half rate (HR) channels along with their associated control
channels (i.e., the fast associated control channel (FACCH) and the slow
associated control channel (SACCH/T) (half rate)). Voice services over
adaptive multi-user channels on one slot (VAMOS) may be used for voice
service configurations for one timeslot 979 by network control for three,
four or five wireless communication devices 104 without telling each
wireless communication device 104 involved.

[0073] The symbols shown are a simplified version of the resource usage. A
legacy full rate speech (FR) may use the entire symbol, which only has 1
bit, and all of the frame number (FN). Hence, one unit of resource (i.e.,
one timeslot 979) may serve one wireless communication device 104 at any
time. However, using the existing half rate speech (HR) service, based on
Gaussian minimum shift keying (GMSK) modulation, the unit of resource may
be divided on the frame number (FN) dimension. Thus, two wireless
communication devices 104 may be served from one transmit channel (TCH)
resource (classified by an even frame number (FN) and an odd frame number
(FN)). When the radio frequency (RF) conditions are good enough to
support half rate speech (HR), capacity gain may be achieved. In the
voice services over adaptive multi-user channels on one slot (VAMOS)
mode, which is based on adaptive quadrature phase shift keying (AQPSK)
modulation, two bits/symbol may provide another dimension (i.e., the
number of bits per symbol on top of the previous half rate speech (HR)
scheme). Thus, a base station 102 using voice services over adaptive
multi-user channels on one slot (VAMOS) may support up to four half rate
speech (HR) voice services over adaptive multi-user channels on one slot
(VAMOS) calls in one transmit channel (TCH) resource (i.e., voice
services over adaptive multi-user channels on one slot (VAMOS) timeslots
979) when the radio frequency (RF) conditions are good enough to support
adaptive quadrature phase shift keying (AQPSK) with half rate speech (HR)
codecs, including Adaptive Multi-Rate (AMR) half rate speech (HR).

[0074] The variety of Circuit Switched (CS) services for a legacy system
is shown by the first two blocks (timeslots 978a-b), which can support up
to two wireless communication devices 104. By using voice services over
adaptive multi-user channels on one slot (VAMOS), additional wireless
communication devices 104 per timeslot 979 may be used (e.g., up to four
total). The channel organization for the transmit channel (TCH), the fast
associated control channel (FACCH) and the slow associated control
channel (SACCH/T) (half rate) in voice services over adaptive multi-user
channels on one slot (VAMOS) mode may be compatible with the legacy mode.
A voice services over adaptive multi-user channels on one slot (VAMOS)
level 1 wireless communication device 104 does not have any differences
as far as channel organization is concerned. Voice services over adaptive
multi-user channels on one slot (VAMOS) level 1 is a downlink advanced
receiver performance (DARP) based solution. Voice services over adaptive
multi-user channels on one slot (VAMOS) level 2 can enable further
performance improvement with the knowledge of both training sequence
codes (TSCs) in the pair and further slow associated control channel
(SACCH) channel shift to maximize performance.

[0075]FIG. 10 is a block diagram illustrating one embodiment of the voice
services over adaptive multi-user channels on one slot (VAMOS) downlink
physical layer functionality of a base station 102. A pair of
corresponding bits from the transmit channels (TCHs) and the associated
control channels in a voice services over adaptive multi-user channels on
one slot (VAMOS) pair may be mapped on to an adaptive quadrature phase
shift keying (AQPSK) modulation symbol with the assigned training
sequence codes (TSCs). The first set of transmit channel (TCH) burst bits
1080a may correspond to a first wireless communication device 104 and the
second set of transmit channel (TCH) burst bits 1080b may correspond to a
second wireless communication device 104.

[0076] The first set of transmit channel (TCH) burst bits 1080a may be
passed through a binary phase shift keying (BPSK) 1081a on the inphase
(I) axis, an amplifier 1082 with a gain of cos(α), a phase shift
1084a of

π 2 * k ##EQU00001##

on the kth symbol and pulse shaping A 1085. The second set of transmit
channel (TCH) burst bits 1080b may be passed through a binary phase shift
keying (BPSK) 108 lb on the quadrature (Q) axis, an amplifier 1083 with a
gain of sin(α), a phase shift 1084b of

π 2 * k ##EQU00002##

on the kth symbol and pulse shaping B 1086. The first set of transmit
channel (TCH) burst bits 1080a and the second set of transmit channel
(TCH) burst bits 1080b may then be combined using an adder 1087 and
passed through an RF modulator and a power amplifier 1088 before being
transmitted by the base station 102.

[0077]FIG. 11 is a flow diagram of a method 1100 for preventing dropped
voice calls. The method 1100 may be performed by a base station 102 or
other access-point type component in one embodiment of the present
invention. The base station 102 may receive 1102 multiple slow associated
control channel (SACCH) reports from multiple wireless communication
devices 104. Some of the wireless communication devices 104 may be legacy
downlink advanced receiver performance (DARP) phones. Thus, these
wireless communication devices 104 may be based on single antenna
interference cancellation (SAIC) and can be used to decode voice services
over adaptive multi-user channels on one slot (VAMOS) adaptive quadrature
phase shift keying (AQPSK) modulated RF signals.

[0078] The wireless communication devices 104 may need to do time tracking
and frequency tracking This is because there is no perfect system in a
live network. Time tracking and frequency tracking may result in a
constant interference presented by adaptive quadrature phase shift keying
(AQPSK). If adaptive quadrature phase shift keying (AQPSK) is constantly
used, the wireless communication devices 104 may track the wrong time and
frequency.

[0079] The base station 102 may identify 1104 one or more wireless
communication devices 104 that appear to have a bad received signal
quality (Rxqual). The base station 102 may then adjust 1106 the
sub-channel power imbalance ratio (SCPIR) so that the base station 102
gives occasional and random favorable power imbalance to the indentified
wireless communication devices 104 over the corresponding paired wireless
communication device 104. This adjustment may range from slight to
extreme. In addition, the adjustment can be performed on a dynamic basis.
For example, in some embodiments, the adjustment may result in the
corresponding paired wireless communication device 104 missing one burst.

[0080] In other embodiments, additional bursts may be missed (e.g.,
ranging from 2-20). Preferably, however, the point is to miss as few
bursts as possible so as not to degrade voice quality to unacceptable
levels (i.e., voice traffic becomes unintelligible to users or surpasses
network thresholds). The adaptive scheme may stop the sub-channel power
imbalance ratio (SCPIR) from progressing towards causing further damaging
bursts. A call may be dropped if the slow associated control channel
(SACCH) has been lost for a predefined number of bursts or amount of time
that may be set by the network. If a call is dropped, the system may
declare a radio link failure.

[0082] Thus, with very little compromise on speech quality, the network
can keep a voice call alive that would likely otherwise be dropped. This
is a problem faced by billions of wireless communication devices 104 in
the live network. Embodiments of the present invention, such as method
1100 provide an adaptive, practical and effective solution to help legacy
downlink advanced receiver performance (DARP) wireless communication
devices 104 work in voice services over adaptive multi-user channels on
one slot (VAMOS) mode. The corresponding paired wireless communication
device 104 (i.e., the wireless communication device 104 with the
perceived better received signal quality (Rxqual)) may miss one burst in
a few seconds. This may not cause any issues for the user experience.
This is because missing one burst in a few seconds does not significantly
degrade the perceived voice quality.

[0083] A wireless communication device 104 may be capable of discerning
the changes in adaptive quadrature phase shift keying (AQPSK)/sub-channel
power imbalance ratio (SCPIR) implemented by a base station 102. The
wireless communication device 104 may generate slow associated control
channel (SACCH) reports. Generated slow associated control channel
(SACCH) reports may be transmitted to a base station 102. In response,
the base station 102 may adjust the sub-channel power imbalance ratio
(SCPIR) to the wireless communication device 104. The wireless
communication device 104 may perform adaptive burst processing according
to the discerned changes to obtain the best performance in terms of the
bit error rate (BER) and the frame error rate (FER). In some examples,
the adaptation can be such that the BER and/or FER are scaled or ranged
to provide acceptable voice quality for end users. These can be modified
as desired and/or required by system performance. In other examples, the
adaptive processing can yield BER and/or FER that prevents a voice call
from being unintelligible by end users and/or from being dropped.

[0084]FIG. 12 illustrates two adaptive quadrature phase shift keying
(AQPSK) constellations 1291a-b for use in one embodiment of the present
invention. Other adaptive quadrature phase shift keying (AQPSK)
constellation 1291 may also be used. Each wireless communication device
104 may be given a binary phase shift keying (BPSK) constellation with
progressive 90 degree rotation on a symbol basis to keep the signal
compatible with the existing Gaussian minimum shift keying (GMSK)
modulation so that legacy wireless communication devices 104 may also be
used in voice over adaptive multi-user channels on one slot (VAMOS) mode.

[0085] The two binary phase shift keying (BPSK) constellations of paired
wireless communication devices 104 may be 90 degrees apart. A binary
phase shift keying (BPSK) constellation 1289a of a first wireless
communication device 104 and a binary phase shift keying (BPSK)
constellation 1290a of a second wireless communication device 104 are
shown in the first adaptive quadrature phase shift keying (AQPSK)
constellation 1291a. Each of the sub-channels may have different power
levels, as is illustrated by the binary phase shift keying (BPSK)
constellation 1289b corresponding to a first wireless communication
device 104 and the binary phase shift keying (BPSK) constellation 1290b
corresponding to a second wireless communication device 104 of the second
adaptive quadrature phase shift keying (AQPSK) constellation 1291b. The
base station 102 may adjust these sub-channel power imbalances (i.e., the
sub-channel power imbalance ratio (SCPIR)) such that a wireless
communication device 104 with a bad received signal quality (Rxqual) may
receive an occasional and random favorable power imbalance.

[0086] The value of the sub-channel power imbalance ratio (SCPIR) is given
by SCPIR=20 log10 (tan α)) and is in decibels (dB). Table 1
gives some angles a and their corresponding sub-channel power imbalance
ratios (SCPIR).

[0087]FIG. 13 illustrates certain components that may be included within
a base station 1302. A base station 1302 may also be referred to as, and
may include some or all of the functionality of, an access point, a
broadcast transmitter, a NodeB, an evolved NodeB, etc. The base station
1302 includes a processor 1303. The processor 1303 may be a general
purpose single- or multi-chip microprocessor (e.g., an ARM), a special
purpose microprocessor (e.g., a digital signal processor (DSP)), a
microcontroller, a programmable gate array, etc. The processor 1303 may
be referred to as a central processing unit (CPU). Although just a single
processor 1303 is shown in the base station 1302 of FIG. 13, in an
alternative configuration, a combination of processors (e.g., an ARM and
DSP) could be used.

[0088] The base station 1302 also includes memory 1305. The memory 1305
may be any electronic component capable of storing electronic
information. The memory 1305 may be embodied as random access memory
(RAM), read-only memory (ROM), magnetic disk storage media, optical
storage media, flash memory devices in RAM, on-board memory included with
the processor, EPROM memory, EEPROM memory, registers and so forth,
including combinations thereof

[0089] Data 1307a and instructions 1309a may be stored in the memory 1305.
The instructions 1309a may be executable by the processor 1303 to
implement the methods disclosed herein. Executing the instructions 1309a
may involve the use of the data 1307a that is stored in the memory 1305.
When the processor 1303 executes the instructions 1309a, various portions
of the instructions 1309b may be loaded onto the processor 1303, and
various pieces of data 1307b may be loaded onto the processor 1303.

[0090] The base station 1302 may also include a transmitter 1311 and a
receiver 1313 to allow transmission and reception of signals to and from
the base station 1302. The transmitter 1311 and receiver 1313 may be
collectively referred to as a transceiver 1315. An antenna 1317 may be
electrically coupled to the transceiver 1315. The base station 1302 may
also include (not shown) multiple transmitters, multiple receivers,
multiple transceivers and/or additional antennas.

[0091] The base station 1302 may include a digital signal processor (DSP)
1321. The base station 1302 may also include a communications interface
1323. The communications interface 1323 may allow a user to interact with
the base station 1302.

[0092] The various components of the base station 1302 may be coupled
together by one or more buses, which may include a power bus, a control
signal bus, a status signal bus, a data bus, etc. For the sake of
clarity, the various buses are illustrated in FIG. 13 as a bus system
1319.

[0093]FIG. 14 illustrates certain components that may be included within
a wireless communication device 1404. The wireless communication device
1404 may be an access terminal, a mobile station, a user equipment (UE),
etc. The wireless communication device 1404 includes a processor 1403.
The processor 1403 may be a general purpose single- or multi-chip
microprocessor (e.g., an ARM), a special purpose microprocessor (e.g., a
digital signal processor (DSP)), a microcontroller, a programmable gate
array, etc. The processor 1403 may be referred to as a central processing
unit (CPU). Although just a single processor 1403 is shown in the
wireless communication device 1404 of FIG. 14, in an alternative
configuration, a combination of processors (e.g., an ARM and DSP) could
be used.

[0095] Data 1407a and instructions 1409a may be stored in the memory 1405.
The instructions 1409a may be executable by the processor 1403 to
implement the methods disclosed herein. Executing the instructions 1409a
may involve the use of the data 1407a that is stored in the memory 1405.
When the processor 1403 executes the instructions 1409, various portions
of the instructions 1409b may be loaded onto the processor 1403, and
various pieces of data 1407b may be loaded onto the processor 1403.

[0096] The wireless communication device 1404 may also include a
transmitter 1411 and a receiver 1413 to allow transmission and reception
of signals to and from the wireless communication device 1404 via an
antenna 1417. The transmitter 1411 and receiver 1413 may be collectively
referred to as a transceiver 1415. The wireless communication device 1404
may also include (not shown) multiple transmitters, multiple antennas,
multiple receivers and/or multiple transceivers.

[0097] The wireless communication device 1404 may include a digital signal
processor (DSP) 1421. The wireless communication device 1404 may also
include a communications interface 1423. The communications interface
1423 may allow a user to interact with the wireless communication device
1404.

[0098] The various components of the wireless communication device 1404
may be coupled together by one or more buses, which may include a power
bus, a control signal bus, a status signal bus, a data bus, etc. For the
sake of clarity, the various buses are illustrated in FIG. 14 as a bus
system 1419.

[0099] The techniques described herein may be used for various
communication systems, including communication systems that are based on
an orthogonal multiplexing scheme. Examples of such communication systems
include Orthogonal Frequency Division Multiple Access (OFDMA) systems,
Single-Carrier Frequency Division Multiple Access (SC-FDMA) systems, and
so forth. An OFDMA system utilizes orthogonal frequency division
multiplexing (OFDM), which is a modulation technique that partitions the
overall system bandwidth into multiple orthogonal sub-carriers. These
sub-carriers may also be called tones, bins, etc. With OFDM, each
sub-carrier may be independently modulated with data. An SC-FDMA system
may utilize interleaved FDMA (IFDMA) to transmit on sub-carriers that are
distributed across the system bandwidth, localized FDMA (LFDMA) to
transmit on a block of adjacent sub-carriers, or enhanced FDMA (EFDMA) to
transmit on multiple blocks of adjacent sub-carriers. In general,
modulation symbols are sent in the frequency domain with OFDM and in the
time domain with SC-FDMA.

[0100] In the above description, reference numbers have sometimes been
used in connection with various terms. Where a term is used in connection
with a reference number, this is meant to refer to a specific element
that is shown in one or more of the Figures. Where a term is used without
a reference number, this is meant to refer generally to the term without
limitation to any particular Figure.

[0101] The term "determining" encompasses a wide variety of actions and,
therefore, "determining" can include calculating, computing, processing,
deriving, investigating, looking up (e.g., looking up in a table, a
database or another data structure), ascertaining and the like. Also,
"determining" can include receiving (e.g., receiving information),
accessing (e.g., accessing data in a memory) and the like. Also,
"determining" can include resolving, selecting, choosing, establishing
and the like.

[0102] The phrase "based on" does not mean "based only on," unless
expressly specified otherwise. In other words, the phrase "based on"
describes both "based only on" and "based at least on."

[0103] The term "processor" should be interpreted broadly to encompass a
general purpose processor, a central processing unit (CPU), a
microprocessor, a digital signal processor (DSP), a controller, a
microcontroller, a state machine, and so forth. Under some circumstances,
a "processor" may refer to an application specific integrated circuit
(ASIC), a programmable logic device (PLD), a field programmable gate
array (FPGA), etc. The term "processor" may refer to a combination of
processing devices, e.g., a combination of a DSP and a microprocessor, a
plurality of microprocessors, one or more microprocessors in conjunction
with a DSP core, or any other such configuration.

[0104] The term "memory" should be interpreted broadly to encompass any
electronic component capable of storing electronic information. The term
memory may refer to various types of processor-readable media such as
random access memory (RAM), read-only memory (ROM), non-volatile random
access memory (NVRAM), programmable read-only memory (PROM), erasable
programmable read only memory (EPROM), electrically erasable PROM
(EEPROM), flash memory, magnetic or optical data storage, registers, etc.
Memory is said to be in electronic communication with a processor if the
processor can read information from and/or write information to the
memory. Memory that is integral or external to a processor can be in
electronic communication with the processor (e.g., direct or indirect
electrical communication).

[0105] The terms "instructions" and "code" should be interpreted broadly
to include any type of computer-readable statement(s). For example, the
terms "instructions" and "code" may refer to one or more programs,
routines, sub-routines, functions, procedures, etc. "Instructions" and
"code" may comprise a single computer-readable statement or many
computer-readable statements.

[0106] The functions described herein may be implemented in software or
firmware being executed by hardware. The functions may be stored as one
or more instructions on a computer-readable medium. The terms
"computer-readable medium" or "computer-program product" refers to any
tangible storage medium that can be accessed by a computer or a
processor. By way of example, and not limitation, a computer-readable
medium may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk
storage, magnetic disk storage or other magnetic storage devices, or any
other medium that can be used to carry or store desired program code in
the form of instructions or data structures and that can be accessed by a
computer. Disk and disc, as used herein, includes compact disc (CD),
laser disc, optical disc, digital versatile disc (DVD), floppy disk and
Blu-ray® disc where disks usually reproduce data magnetically, while
discs reproduce data optically with lasers. It should be noted that a
computer-readable medium may be tangible and non-transitory. The term
"computer-program product" refers to a computing device or processor in
combination with code or instructions (e.g., a "program") that may be
executed, processed or computed by the computing device or processor. As
used herein, the term "code" may refer to software, instructions, code or
data that is/are executable by a computing device or processor.

[0107] Software or instructions may also be transmitted over a
transmission medium. For example, if the software is transmitted from a
website, server, or other remote source using a coaxial cable, fiber
optic cable, twisted pair, digital subscriber line (DSL), or wireless
technologies such as infrared, radio, and microwave, then the coaxial
cable, fiber optic cable, twisted pair, DSL, or wireless technologies
such as infrared, radio, and microwave are included in the definition of
transmission medium.

[0108] The methods disclosed herein comprise one or more steps or actions
for achieving the described method. The method steps and/or actions may
be interchanged with one another without departing from the scope of the
claims. In other words, unless a specific order of steps or actions is
required for proper operation of the method that is being described, the
order and/or use of specific steps and/or actions may be modified without
departing from the scope of the claims.

[0109] Further, it should be appreciated that modules and/or other
appropriate means for performing the methods and techniques described
herein, such as those illustrated by FIG. 11, can be downloaded and/or
otherwise obtained by a device. For example, a device may be coupled to a
server to facilitate the transfer of means for performing the methods
described herein. Alternatively, various methods described herein can be
provided via a storage means (e.g., random access memory (RAM), read only
memory (ROM), a physical storage medium such as a compact disc (CD) or
floppy disk, etc.), such that a device may obtain the various methods
upon coupling or providing the storage means to the device. Moreover, any
other suitable technique for providing the methods and techniques
described herein to a device can be utilized.

[0110] It is to be understood that the claims are not limited to the
precise configuration and components illustrated above. Various
modifications, changes and variations may be made in the arrangement,
operation and details of the systems, methods, and apparatus described
herein without departing from the scope of the claims.